Awesome
Good choice of music (altho somewhat glitchy, I'll guess it's cuz of the compression)
Controls kept good and simple, cool. Custom graphics but even better than sprites. Diversified boss attacks, lots of stages, which aren't linear...
I give it a 5/5 because of comparison to other amateur work. If this was a commercial game or something I'd give it a 3.5/5 tho because there isn't much put on the storyline so it's not very rewarding to get to the end.
Oh and some boss fights were....ugh, man....last boss's first phase attacks were too quick. (If you stand at the wrong place you get hurt automatically when the fists appear)
Thanks god you included a save load system too.